Personal sound amplification products (PSAPs) are accessible and affordable devices for hearing-impaired individuals who would otherwise not seek professional treatment. Like self-fitted hearing aids, PSAP use does not involve any professional audiology service. This pilot study investigated the impact of different instruction levels on PSAP use among participants with mild to moderate sensorineural hearing loss. Participants were given either basic written instructions or premium audiology services on how to use a PSAP. Preliminary data suggested that the participants’ knowledge and skills in operating the PSAP, as well as their hearing outcomes, were similar after six weeks of PSAP use.
BENEFITS & LIMITATIONS
Although PSAPs are not intended for treating hearing loss, their availability for direct consumer purchase may sound appealing to those with hearing needs. Notably, the Food and Drug Administration (FDA) now is required to develop regulations for over-the-counter (OTC) hearing aids. It is possible that PSAPs will be merged with OTC hearing aids along with the FDA regulations.
Because PSAPs can be purchased without a hearing evaluation, some people may purchase a PSAP but not know if it is appropriate for their hearing needs. Other concerns about PSAP use include whether conventional prescription methods are close to an individual's preferred settings, whether users can obtain good outcome measures, and whether users can follow the device's written usage instructions successfully (Trends Amplif. 2011;15:184).
There is an ongoing debate that product pricing, extended trial period, and liberal refund policy draw consumers to PSAPs as opposed to traditional hearing aids. On the other hand, some believe that the rise of PSAPs may expand audiology services to more individuals. Some companies that sell PSAPs online have an audiologist on staff for consumer consultation and support. This gives customers access to more device-specific details like smartphone connectivity and information on other assistive devices.
Counseling and aural rehabilitation are unique, audiology-exclusive services that will likely be unbundled and provided in collaboration with companies to improve the communication abilities of more patients. With that in mind, both PSAPs and hearing aid providers can agree on the shared goal of providing amplification for as many hearing-impaired individuals as possible. However, little is known if users can get enough knowledge and skills to effectively use PSAPs or OTC hearing aids and have good outcomes without audiology services. This is critical in advocating for OTC hearing aids.
Specifically, it is crucial to investigate the impact of different levels of audiology service on these direct-to-consumer hearing devices. The goals of this pilot study were to:
• compare the acquired knowledge and skills of PSAP users after getting different levels of instruction (written instructions only or premium audiology service), and
• investigate the impact of these different levels of instruction on the outcomes for PSAP users.
It was hypothesized that providing premium audiology service would result in PSAP users with better knowledge and skills in operating the device and more favorable outcomes, compared with users who only received the basic written instructions.
Four participants between 55 and 80 years old completed the pilot study (two men, two women). All had bilateral and symmetrical mild to moderate sensorineural hearing loss and no previous hearing aid experience. Hearing symmetry was defined as an interaural difference of less than 15 dB HL across the frequencies of 500, 1000, 2000, and 4000 Hz. All participants scored above 26 in the Montreal Cognitive Assessment (MoCA), which ruled out potential cognitive impairment. The local Institutional Review Board approved this study.
The commercially available PSAP used in the study was the CS50+, donated by SoundWorld Solutions (Fig. 1). The device had Bluetooth capacity and an associated application for smartphone use. It had three presets and three programs within each preset. A personal audiogram can be added if desired.
The original user manual of the PSAP was first evaluated using readability measures, including the Flesch Reading Ease and Flesch-Kincaid Grade Level, as well as the Suitability Assessment of Materials (SAM), a rating scale used to evaluate written health care materials. Evidence-based guidelines for designing effective instruction materials for self-fitted hearing devices were observed to develop a new and effective instruction manual for the PSAP (see Skaggs & Ou, AudiologyNow 2017). Two independent audiologists evaluated the new manual for suitability.
A total of two visits were arranged. At the initial visit, all participants went through bilateral pure-tone air (octave frequencies of 250-8,000 Hz) and bone conduction (octave frequencies of 500-4,000 Hz) audiometric tests in a sound-treated booth. The following were also administered at the first and second visits:
• the Abbreviated Profile of Hearing Aid Benefit (APHAB),
• the short form of the Spatial Hearing Questionnaire (SHQ-S; Am J Audiol. 2017;1),
• the short form of the Speech, Spatial and Qualities of Hearing Scale (SSQ12), and
• the screening version of the Hearing Handicap Inventory for the Elderly (HHIE-S) questionnaires.
The participants were assigned to different levels of instruction: Two participants were given basic written instructions only (these participants will be referred to as Basic 1 and Basic 2 users), and the other two were provided with premium audiology service (Premium 1 and Premium 2 users). Basic 1 and Basic 2 each received a pair of the PSAP (one device for each ear), along with its written user instructions. The other two received a pair of the PSAP with its written instructions, as well as an audiologist orientation and verification based on the best practice guidelines from ASHA (Am J Audiol. 1998;7:4).
Fine-tuning was made within the device's capabilities to meet the NAL-NL2 prescription targets. The output sound pressure levels from each device were verified using Audioscan Verifit2 real-ear-measurement equipment. The loudness ratings for both ears were assessed and balanced. The full orientation was provided after the fine-tuning.
After six weeks of using the PSAPs, all participants returned for a final evaluation. The Revised Hearing Aid Skills and Knowledge (HASK) test (adapted from J Am Acad Audiol. 2017;00:1) was used to assess how each participant used the device. The International Outcome Inventory for Hearing Aids (IOI-HA) was collected during the second visit. A higher rating on the IOI-HA, SHQ-S, and SSQ12 was associated with greater benefit and satisfaction. Both aided and unaided speech perception performances were evaluated using the Revised Performance Perceptual Test (R-PPT; Wetmore & Ou, IHOCN 2016). Aided speech intelligibility index was assessed for each ear for the most commonly used program for all participants. An informal exit interview was also conducted to obtain additional subjective outcomes at the end of the session.
Revised HASK test
All participants scored higher in the skills than in the knowledge portion of the revised HASK test (Table 1). The knowledge scores were similar among all participants. The skills scores of Premium 1 and 2 were slightly higher than the other participants. Basic 2 had the poorest performance in this test.
Raw global scores of each participant in the IOI-HA, unaided and aided APHAB, SSQ12, SHQ-S, and HHIE-S are shown in Figure 3. Across the individuals, aided listening conditions typically elicited better scores than unaided. All participants scored higher (better) in the aided SHQ-S condition and lower (better) on the aided HHIE-S. All participants had increased aversiveness to loud sounds with the PSAP devices, and all but one participant had an equal or increased difficulty in reverberant environments.
The Revised Performance-Perception-Test (PPT) included both subjective and objective speech recognition performance (SNR50) using the same QuickSIN test material (Wetmore & Ou, IHOCN 2016). Figure 3 shows both the aided and unaided data on all participants. Two participants self-perceived an improvement of 2 dB in the aided condition, while three participants performed similarly between aided and unaided conditions when tested objectively. The aided SII values of the most commonly used program ranged from 45-70 percent for the soft speech (50 dB SPL) and 66-84 percent for the average speech (70 dB SPL).
The results did not support the first hypothesis that getting premium audiology service would result in better knowledge and skills in using a PSAP, compared with just receiving basic written instructions. The revised HASK test revealed similar results between the participants who received different levels of instruction. It was unexpected that Basic 1 earned the highest knowledge score. Premium 1 and Basic 1, both female, earned the highest skill scores, followed by Premium 2 and Basic 2. The Premium participants had the greatest difficulty addressing the storage and troubleshooting portions of the knowledge subtest, and the phone-use portion of the skills subtest. The Basic users also had difficulty in the phone-use part of the skills subtest and in PSAP mode changes in the knowledge subtest.
The results also did not support the second hypothesis that the availing premium audiology service could result in favorable PSAP user outcomes. In this pilot study, outcome measurements included IOI-HA, unaided and aided APHAB, SSQ12, SHQ-S, HHIE questionnaires, and an informal exit interview. The higher the participant's score in the IOI-HA, the greater the benefit of the device. If the first item (at least one hour of daily PSAP use) and the second item (helped moderately in the situation where users most want to hear better) of the IOI-HA were used to indicate the success in PSAP use, then Basic 1 and 2 were successful users.
All participants reported hearing difficulties in the subscales of reverberant environments, aversiveness, and ease of communication of the APHAB. Premium 1 and Basic 2 had similar difficulties in these same environments while using the PSAP, while Premium 2 had perceived more problems and Basic 1 had the least difficulties. The higher the number scored on the SHQ-S, the greater the self-reported spatial hearing ability is perceived. All participants perceived better spatial hearing ability while using the PSAP. It appeared that the Basic users perceived more improvement in spatial hearing ability compared with the Premium users.
The SSQ12 questionnaires measure the subjective ability and experience while hearing and listening in different communication situations. A greater score indicates improved ability to listen in the hypothetical environment. The SSQ12 revealed that Premium 1 felt a decreased listening ability with the PSAP. Basic 2 observed similar listening abilities while using the PSAP, while Premium 2 and Basic 1 indicated improved listening abilities in all the hypothetical questionnaire situations.
The HHIE-S measured perceived emotional and situational hearing handicaps in aided and unaided listening conditions. Both Basic users and Premium 2 perceived a slight reduction in hearing handicap while using the PSAPs. Premium 1 perceived having the same hearing handicap. In addition to the subjective questionnaires, the speech recognition test was measured using the Revised PPT. It appeared that the Premium users performed better when aided. One Premium and one Basic user self-perceived better performance in aided than in unaided condition.
The results from this pilot study were consistent with the recent study by Humes, et al., that investigated the effects of two service-delivery models (the best practice and consumer-decides models) on hearing aid outcomes in older adults with mild to moderate hearing loss (Am J Audiol. 2017;26:53).
The informal exit interview provided insights into some qualities of the PSAPs that were not evaluated by the other outcome measures. Excessive feedback and wind noise were major concerns for three of the four participants. The participants with normal or near-normal low-frequency hearing thresholds complained of occlusion. The Premium users’ major complaint was that the PSAPs were loud and overwhelming, even with volume controls. The most frequent listening situation where participants perceived the most benefit was while watching television. Premium 2, who had the most severe hearing loss, previously considered purchasing a similar device but changed his mind after this experience. Both Basic users reported negative impressions of the size and appearance of the device. After perceiving improved hearing with this PSAP, Basic 2 decided to consider amplification options for everyday use. Premium 2 reported that should her hearing loss decline, amplification options would be considered. Premium users indicated that the written instructions were helpful to refer to after receiving the formal orientation in the audiology office. The Premium users were the only ones who used the different PSAP modes. The Basic users also reported getting benefits from the written instructions, but both denied using the PSAP modes for different environments. One participant indicated an interest in purchasing a similar device for a reduced price that does not include any audiology service, and two participants reported an improved interest in pursuing amplification options after the study.
LIMITATIONS & CONCLUSION
The conclusions are preliminary for this pilot study. It should be noted that the basic written instruction used in the study was not the original one provided by the manufacturer. Compared with the original user instruction, the revised one may have helped users better understand PSAP use. Therefore, the outcome differences between the written instruction and the premium audiology service might be diminished. In addition, the variation in subjective outcome measurements between the Basic and Premium users could be due to expectations. Having a premium audiology service could have increased the expectations of Premium users from PSAP use. This study shows that providing patients with basic written instruction could result in similar knowledge and skill outcomes in PSAP use, compared with giving premium audiology service. While outcome measurements revealed a variety of results across participants, all participants indicated getting some benefits from the PSAPs.
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